Miyaoka Y, Shingai T, Takahashi Y, Nakamura J I, Yamada Y
Department of Physiology, Niigata University School of Dentistry, Japan.
Brain Res Bull. 1998;45(1):95-100. doi: 10.1016/s0361-9230(97)00313-4.
The responsiveness of the parabrachial region to electrical stimulation of the superior laryngeal nerve was first examined in anesthetized rats. Action potentials were recorded in 30 parabrachial sites by single and train electrical pulses to the superior laryngeal nerve. The average latency, from the onset of stimulation to the first action potentials, was 9.9 ms (range, 6.5-18.8 ms). The responsiveness of parabrachial neurons to chemical stimulation of the laryngeal region was next examined using anesthetized, immobilized, and artificially ventilated rats in which the chorda tympani and glossopharyngeal nerves were bilaterally sectioned. Taste stimuli were applied to the laryngeal region through a tracheal tube and rinsed with 0.15 NaCl. A total of 66 responses were recorded from 26 neurons. The most effective stimulus for these neurons was 0.03 M hydrochloric acid, followed by 0.01 M quinine hydrochloride, 0.5 M sodium chloride, 0.5 M sucrose, and distilled water. Seven responses were derived from 0.15 NaCl. These neurons were mainly located in a posterodorsolateral part of the parabrachial nucleus. These results suggest that chemical signals from the laryngeal region are transmitted to the parabrachial nucleus through the superior laryngeal nerve.
